The increasingly rapid development in the field of what are known as vehicle-to-X communication systems and the associated technologies provides a large number of novel options for reducing or even completely avoiding risks and hazard situations in road traffic. Furthermore, it is known practice to use vehicle-to-X communication systems to increase driving comfort, for example as part of a traffic light phase assistant, or else for commercial applications and for entertainment purposes for the passengers. A problem associated with this development is ensuring the necessary reliability and particularly data integrity of the transmitted vehicle-to-X information, however, since such information can be used as a basis for autonomous interventions in the vehicle control and for gaining access to essential vehicle functions. A piece of incorrect or, in the worst case, even maliciously falsified vehicle-to-X information can therefore have serious consequences and needs to be reliably identified as untrustworthy.
In this connection, DE 10 2011 077 998 A1 discloses a method for information validation for a vehicle-to-X message by means of ambient sensors. In this context, the information content of a piece of vehicle-to-X information can be reliably validated even if the ambient sensors capture the information content described by the vehicle-to-X information only for a short time or with constant interruptions. Hence, it is possible for vehicle-to-X information to be validated or rejected as not sufficiently trustworthy even in situations with only restricted ambient sensing opportunities. If the vehicle-to-X information is validated according to the method proposed in DE 10 2011 077 998 A1, it has a sufficiently high level of reliability for intervention in the vehicle control.
DE 10 2007 030 430 A1 describes a method for transmitting vehicle-relevant information in and from a vehicle. What is known as a transmission control unit is used to evaluate information received from various communication means, such as mobile radio means or WLAN means, and then to transmit it to mobile terminals carried in the vehicle. In this case, the transmission control unit may comprise a security module that allows communication and data interchange with transmitters situated outside the vehicle in secure form. In order to ensure the secure form of the data interchange, both the information to be transmitted and the information received is stored and monitored. At the same time, attacks on the outside on the information, such as an eavesdropping attempt, are fended off. In addition, the option of transmitting information in encrypted form is described.
DE 10 2011 079 052 A1 discloses a method and a system for validating a vehicle-to-X message. In this case, a wirelessly transmitted vehicle-to-X message is received by an antenna arrangement that has at least two antenna elements, wherein the electromagnetic field strength of the vehicle-to-X message is picked up by the antenna elements with different power densities on account of different, direction-dependent reception characteristics of the antenna elements. The transmitted vehicle-to-X message furthermore comprises an absolute position—based on GPS data—for the transmitter, and the receiver of the vehicle-to-X message uses its own position to calculate a first relative position for the transmitter in relation to the receiver from said absolute position. In addition, the receiver determines a second relative position for the transmitter in relation to the receiver from the ratio of the power densities picked up. A comparison of the first relative position with the second relative position can then be used to validate the received vehicle-to-X message if both positions match, or to reject it if the positions differ from one another.
The data integrity precautions or data integrity methods that are known from the prior art in connection with vehicle-to-X communication have disadvantages for various reasons, however. By way of example, vehicle-to-X messages must, as one alternative, be signed or encrypted in complex fashion on account of the high data integrity requirements, which requires comparatively powerful hardware for coding and decoding. This hardware in turn is associated with a correspondingly high level of cost involvement, which renders such methods unattractive. If resorting to checking the information content of the received vehicle-to-X messages by means of ambient sensors, a sufficient number of different types of ambient sensors is required on the vehicle in order to be able to capture as large as possible a number of different pieces of information and compare them with the information content of the received vehicle-to-X messages. In addition, the various operating principles of the communication means and of the ambient sensors, the orientation of the ambient sensors or simply the absence of ambient sensors mean that it is often not possible to check a vehicle-to-X message in this way. The use of a directionally selective antenna in turn often allows no clear inferences as to the position of the transmitter, since the electromagnetic field of the transmitted vehicle-to-X message is subject to a large number of influences on the beam path to the antenna of the receiver. This decreases the reliability and the availability of such a method.